It has been known since the early 1800s that when two dissimilar conductors are joined into a loop and a temperature differential is maintained between the two end junctions, an electromotive force is generated causing a current to flow.
Since the time of this discovery, various combinations of material, configurations of units and/or sizes have allowed this principle to be utilized to use heat to generate electricity having a twofold effect, i.e., removing heat from where it is often not wanted and creating an electromotive force which likewise can be used for its obvious benefit. By reversing the process, an electric current can be applied to the thermocouple causing the unit to serve as a cooling device.
The early devices were fabricated of hardware, such as hard wire and other physically large components, but it was determined that the principle likewise should work on a smaller scale. The devices were manufactured using electrodepositing, etching and similar methods producing devices which continued to function as predicted, but of a much smaller size. Obviously the size of the device, the material from which it is manufactured, the number of units, and certainly the difference in temperature between the two junctions will each determine independently the amount of power that is generated. Obviously an optimal combination should exist.
Prior art known by the present inventor include U.S. Pat. No. 3,018,312 granted to Cornish et al, Jan. 3, 1962 which discloses a plurality of materials used for thermoelectrical conductors.
U.S. Pat. No. 3,051,767 granted to Frederick et al, Aug. 28, 1962 discloses thermoelectric devices and thermoelements.
U.S. Pat. No. 3,057,940 granted to Fritts Oct. 9, 1962 discloses a thermoelectric generator of a particular structure, such that the expansion or contraction of the elements caused by the temperature changes is minimized.
U.S. Pat. No. 3,090,206 granted to Anders May 21, 1963 discloses thermoelectric devices and circuits therefor, including specific structure to improve the efficiency thereof.
U.S. Pat. No. 3,279,954 granted to Cody et al, Oct. 18, 1966 discloses a thermoelectric device, including a silicon germanium alloy element.
U.S. Pat. No. 3,400,452 granted to Emley Sep. 10, 1968 discloses a method of producing tubular thermoelectric devices reducing the damage to the elements caused by mechanical deformation during fabrication.
U.S. Pat. No. 3,554,815 granted to Osborn Jan. 12, 1971 discloses a thin thermoelectric device, including a thin flexible nonconductive film having noncontacting bands on opposite sides of a film in conductive electrical association.
U.S. Pat. No. 3,723,189 granted to Zahn Mar. 27, 1973 discloses a staged thermoelectric device, wherein the segments of each stage are connected thermally in parallel and interconnected thermally in series at the stage level.
U.S. Pat. No. 3,900,603 granted to Rittmayer et al, Aug. 19, 1975 discloses a method for producing a thermoelectric generator by vapor depositing a semiconductor compound.
U.S. Pat. No. 4,095,998 granted to Hanson Jun. 20, 1978 discloses a thermoelectric voltage generator specifically designed to absorb the heat from an automobile exhaust system, generating electricity for use in the vehicle.
U.S. Pat. No. 4,251,290 granted to Gomez Feb. 17, 1981 discloses a thermopile formed of conductor elements, wherein the junctions are of a large cross section increasing the efficiency of the unit.
U.S. Pat. No. 4,257,822 granted to Gomez Mar. 24, 1981 discloses a continuous thermopile of a repetitive shape manufactured by a plating process.
U.S. Pat. No. 4,276,441 granted to Wilson Jun. 30, 1981 discloses a thermoelectric generator fabricated of printed conductive ink upon a suitable substrate.
U.S. Pat. No. 4,343,960 granted to Eguchi et al, Aug. 10, 1982 discloses a thermopile fabricated by a photo-etching technique.
U.S. Pat. No. 4,438,291 granted to Eichelberger et al, Mar. 20, 1984 discloses a low cost thermocouple fabricated by a screen printing technique.
U.S. Pat. No. 4,444,991 granted to Beale on Apr. 24, 1984 discloses a high efficiency thermopile, wherein the junction of dissimilar materials at the higher temperature is of a larger than normal cross section of the elements at the lower temperature. The device is manufactured utilizing a thin film technology.
U.S Pat. No. 4,459,428 granted to Chou on Jul. 10, 1984 discloses a thermoelectric device, wherein thermocouples are disposed between a pair of copper plate segments having a thin film ceramic insulator.